Our major goals are to investigate the mechanism/s of transformation by the Sprague-Dawley leukemia virus (SD--RaLV) and to understand the molecular pathways involved in the generation of rat saracoma virus (RaSV). We have developed in vitro systems to identify sequential changes appearing at various levels of SD-RaLV induced transformation and for rescuing RaSV from chemically transformed cells. With the use of genomic and subgenomic molecular probes of SD-RaLV and RaSV proviral DNA, we will analyze the DNA and RNA of these cells from normal to pretransformed to the transformed stages. Further, we will a tempt to identify cellular gene/s that may be preferentially expressed in SD-RaLV transformed cell but are absent or constitutively present in normal cells. Also, we propose to characterize RaSV related cellular oncogenes (c-ras) expressed in the chemically transformed cells and to delineate the sequential steps in the biogenesis of RaSV in the rat cells. Since the RaSV induced transformation specific protein (p29) is a fusion product of RaLV gag p15 sequences and C-ras gene product, we will also determine if p15 sequences are required for the maintenance of RaSV induced transformation. Moreover, nucleic acid sequence analysis of creitical portions of both RaLV and RaSV would help in a better understanding of the structure and orientation of the c-ras genes in relation to the promoter sequences and to RaLV genes.